Deadlock for sliding doors

ABSTRACT

An accessory lock especially adapted for sliding glass doors is described. The locking includes a locking cylinder which has a groove extending axially into the periphery. A housing for the cylinder is rigidly mountable adjacent the edge of a door at a location at which when the door is closed, a strike protruding from the frame for the door opening intersects the path of rotation of the cylinder and is received within the groove. A pin which projects radially outward from the cylinder extends through a transverse slot in the housing. The pin normally rides in the slot when the door is opened or closed. However, such pin is so shaped that upon rotating the same about its own axis 90*, it will coact with the housing slot to prevent rotation of the cylinder when the door is closed, thus trapping the strike and preventing opening of the door.

States Patent" [191 Carvell et al.

[451 Oct. 14, 1975 DEADLOCK FOR SLIDING DOORS [76] Inventors: Bernard J.Carvell, PO. Box 4092, Foster City, Calif. 94404; W. Nelson -Sandf0rd5734 Tucson Drive, San

Jose, Calif. 95150; C. Michael Zimmerman, 160 Redland Road, Woodside,Calif. 94062 22 Filed: Feb. 7, 1974 21 Appl. No.: 440,452

[52] US. Cl. 292/216; 292/78; 292/210;

292/341.l7; 292/DIG. 46 [51] Int. Cl. EOSC 3/04; EOSC 3/14 [58] Field ofSearch 292/57-5 8,

292/78, 216, 304, 210, 73, 261, 341.17, DIG. 42, DIG. 46, DIG. 51

[56] References Cited UNITED STATES PATENTS 278,854 4/1860 Worthen....292/34l.17

462,183 10/1891 Varney 292/210 697,933 4/1902 Blatchley... 292/57770,837 9/1904 Wells 292/78 961,778 6/1910 John 292/57 973,358 10/1910Liers 292/341.17 X 1,657,423 1/1928 VanDuzer.. 292/78 2,116,001 5/1938Sch1age.., 292/57 X 2,978,266 4/1961 Poe 292/57 FOREIGN PATENTS ORAPPLICATIONS 1,205,630 9/1970 United Kingdom 292/216 1,199,916 12/1959France 292/216 Primary Examiner-Paul R. Gilliam Assistant ExaminerCarlF. Pietruszka Attorney, Agent, or FirmC. Michael Zimmerman, Esq.

[ ABS IRACT An accessory lock especially adapted for sliding glass doorsis described. The locking includes a locking cyl-- inder which has agroove extending axially into the periphery. A housing for the cylinderis rigidly mountable adjacent the edge of a door at a location at whichwhen the door is closed, a strike protruding from the frame for the dooropening intersects the path of rotation of the cylinder and is receivedwithin the groove. A pin which projects radially outward from thecylinder extends through a transverse slot in the housing. The pinnormally rides in the slot when the door is opened or closed. However;such pin is so shaped that upon rotating the same about its own axis 90,it will coact with the housing slot to prevent rotation of the cylinderwhen the door is closed, thus trapping the strike and preventing openingof the door.

5 Claims, 10 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of23,912,311

US. Patent 0a. 14, 1975 Sheet 2 of 2 DEADLOCK FOR SLIDING DOORSBACKGROUND OF THE INVENTION The present invention relates to a deadlockfor securely locking an opening closure in its closed position and, moreparticularly, to such a deadlock which is especially useful in lockingsliding doors in a fail-safe and tamper-proof manner.

In the past several years, there has been a sharp rise in the number ofhome burglaries.'In this connection, burglars are gaining unauthorizedentry into most homes without much difficulty. Unauthorized entrythrough sliding glass doors of the type commonly used to provide accessto patios, decks and the like is especially easy. Such sliding doors areoften installed in new housing units, making new homes, which are afavorite target of burglars, particularly vulnerable.

Although most sliding doors are equipped by their manufacturer withlocks of one sort or another, such locks are generally not sufficient toprevent unauthorized entry. For one thing, standard locks for slidingdoors are generally of a relatively flimsy nature, with the result thatthey can be forced to permit a door to be opened. Moreover, most do notprevent lifting of a sliding glass door and consequent removal of itmerely by disengaging it from its tracks.

Because burglars generally wish to avoid the noise associated with thebreaking of glass for entry, the provision of a satisfactory lock on asliding glass door will be a deterrent to burglary. For this reason,many different accessory locks for sliding glass doors have been madeavailable. In general, though, such locks are either inconvenient to useor have other deficiencies which render them less than fullysatisfactory. For example, some accessory locks are simply blocks of onesort or another which sit within the track of the sliding door toprevent it from being opened. Such blocks must, of course, be placedwithin the track after each time the door is opened, and it is notunusual for one to forget or to otherwise fail to perform this task.Other auxiliary locks are designed to be mounted on a floor adjacent thedoor for engagement with it in one way or another to prevent itsopening. Locks of this type often must be installed at a location on thefloor at which they can be tripped over by anyone passing through thedoor opening. Many are also of a somewhat flimsy nature which not onlymakes them susceptible to forcing, but also easily damaged byinadvertent kicking or stepping.

SUMMARY OF THE INVENTION The present invention relates to a deadlockwhich is structurally quite strong and yet quite convenient to use. Inits basic aspects, the deadlock includes a cylindrical locking blockwhich is preferably massive, e.g., solid and of a metal. Such lockingcylinder is provided with an axially extending groove projectingthereinto from its outer periphery. A housing supports the lockingcylinder for rotation on its cylindrical axis and consequent travel ofthe longitudinally extending sides of the groove on a circular path. Thehousing is rigidly mountable adjacent the edge of either an openingclosure, such as a door, or the frame for the opening closure, at alocation at which when the door is closed, a strike protruding from theframe or door will intersect the cylindrical path of the groove sides inthe locking block.

The opposed longitudinally CXlBI'IUlZlg sides of the groove are sopositioned within the block that upon the door or other closure beingclosed, the strike will engage a first one of such groove sides andcause rotation of the locking block in a first direction positioning theother of the groove sides at a location blocking the return path thestrike follows when the door is opened. The second groove side is alsoso positioned in the block that when the door is opened, the strike willengage such second groove side and cause the block to rotate in itsreverse direction in order to both move the second groove side from itsblocking location and again position the first'groove side in the pathof the strike for engagement by it when the door is again closed.Releasable means are provided for selectively preventing rotation of theblock in the reverse direction removing the second groove side fromblocking the return path,

whereby the door will be maintained by the lock in its closed position.The above simple structure will result in the locking cylinder beingbrought to a locking position whenever the door is closed, and beingautomatically cocked whenever the door is opened for subsequent rotationinto the locking position when the door is again closed. Because thepart of the lock which causes the actual locking action is thusautomatically moved to its proper positions whenever the door is openedor closed, the amount of additional effort involved in causing lockingcan be minimized, even though the cylindrical block is generally heavierthan the moving parts of other locking mechanisms.

Most simply, the releasable locking means includes a pin which issecured to the cylindrical locking block and extends generally radiallyoutward therefrom through a slot extending transversely through thehousing. The pin will thus move along such slot upon the rotation of thecylindrical block between the door open and door closed positions. Mostdesirably, the pin is not circular in transverse cross-section where itpasses through the slot, but has a dimension in one direction which isless than its dimension in another direction orthogonal thereto, and thewidth of the slot is such that it will accommodate the sliding movementof-the pin therealong only when the shorter pin dimension extends in thedirection of suchwidth. The result is that by merely rotating the pin,it; will be prevented from sliding along the slot and, hence, thelocking cylinder will be prevented from rotating on its cylindrical axisto remove the same from the return path of the strike. Thus, the actualoperation to cause a desired door locking action by the relativelymassive locking block is a mere rotation of a pin. The slot is enlargedto permit such pin rotation at the location at which the pin ispositioned when the locking cylinder blocks the return path of thestrike in order to permit such pin rotation.

The deadlock of the invention also most desirably includes structurewhich prevents the door from being lifted from its track'whenever it isin its closed position. To this end, transversely extending stops, mostsimply part of the locking cylinder housing, are spaced axially of thelocking block at locations at which when the protruding strike end isengaged within the deadlock, movement of such strike longitudinally orvertically within the locking block groove is constrained by such stops.The prevention of relative vertical movement between the strike and lockwill likewise prevent such vertical movement between the door and frame,the members to which such strike and lock are secured.

Thus, lifting of the door in the frame is prevented at the locklocation.

The invention includes other features and advantages which will becomeapparent or will be described from the following, more detaileddescription of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the two accompanyingsheets of drawings:

FIGS. 1 and 2 are partial isometric views illustrating a preferredembodiment of the deadlock of the invention mounted in position ,toprovide locking for a sliding glass door, FIG. 1 showing the door in itsclosed position with the lock secured, and FIG. 2 illustrating the dooropen;

FIGS. 3 and 4 are enlarged, partial cross sectional views takenrespectively on planes indicated by the lines 3--3 and 44 in FIGS. 1 and2, showing details of the lock construction and its operation;

FIG. 5 is an enlarged, exploded isometric view of the preferredembodiment of the deadlock of the invention;

FIG. 6 is a sectional and broken-away view of the deadlock of theinvention illustrating aspects of its construction;

FIG. 7 is an enlarged, partial sectional view illustrating details ofthe releasable locking means of the preferred embodiment;

FIG. 8 is a sectional view taken on the plane indicated by the lines 8-8in FIG. 7 illustrating the relationship of the pin and slot when thelock is in a door locked position;

FIG. 9 is a sectional view similar to that of FIG. 8 except illustratingthe relationship of the pin and slot when the releasable locking meansis in a door unlocked position; and

FIG. 10 is another sectional view of the releasable locking means takenon a plane indicated by the lines 10-10 in FIG. 7 and illustratingfurther details of its construction.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT With reference first toFIGS. 1 and 2, a preferred embodiment of the deadlock of the invention,generally referred to by the reference numeral 11, is illustratedrigidly mounted adjacent meeting edges of a sliding glass door 12 andthe frame 13 surrounding the opening for such door. The main structure14 of the lock is that portion mounted on the door, at a location atwhich it will coact in a manner to be described with an end 16 of astrike 17 protruding from the door frame 13 into the door opening.

The main structure 14 of the deadlock 11 includes a locking block 18having a circular cylindrical outer periphery. As a particularlyimportant feature of the instant invention, the block 18 is providedwith an axially extending groove 19 which projects generally radiallyinwardly thereof, and the block is rotatable on its cylindrical axis(represented at 21 in FIG. 5) with the result that the opposedlongitudinal sides 22 and 23 of the groove will travel on a circularcylindrical path.

The main structure 14 of the deadlock further includes a housing for therotatable block 18 which is rigidly mountable to the door for supportingsuch block at an appropriate location so that when the door is closed,the cylindrical path of the groove sides 22 and 23 is intersected by theprotruding end 14 of the strike. Such housing is made up by a mainmember 24 having a generally semi-cylindrical reentrant portion defininga cavity 26 within which the cylindrical block 18 is received. As bestillustrated in FIGS. 3 and 4, the cavity 26 has a circular cylindricalsection surface 27 which mates and coacts with the outer periphery ofthe locking block to define the latters rotation and, hence, thecylindrical path of the grooves opposed sides 22 and 23. In thisconnection, it can be noted from FIG. 6 that the cylindrical block 18extends generally for the full length of the cavity and is provided withend projections 28 on the cylindrical axis thereof which are engageablewith the opposed ends 29 of the cavity to define bearings for suchrotation.

The housing also includes a closure plate 31 which closes the cavity 29and retains the cylindrical block 18 therein. More particularly, as canbe seen from FIG. 6, the peripheral edge of the plate fits within arecess 32 at the opening into the cavity. Such plate also includes areentrant arcuate section 33 (see FIG. 5) which acts as a continuationof the cylindrical surface within the cavity.

The main member 24 of the housing is notched longitudinally at 34 todefine, in effect, a slot extending from the exterior of the housinginto the cavity enabling passage of the protruding end 16 of the strikeinto such cavity for coaction with the locking block. FIGS. 3 and 4illustrate such coaction. That is, by comparing FIGS. 3 and 4, it willbe seen that when the door is brought to its closed position, the end 16of the strike will enter through the slot in the housing and engage thelongitudinal side 22 of the groove 19 to rotate the block to bring thegroove side 23 into the position shown in FIG. 3 blocking the returnpath the strike end takes when the door is opened. Thus, every time thedoor is closed,

the locking block 18 is automatically brought into the door lockingposition.

When the door is opened, the strike end 16 will engage the side 23 ofthe groove 19 to rotate the locking block 18 in its reverse direction,assuming, of course, that the deadlock has not been actuated to preventsuch reverse rotation. As can be seen from FIG. 4, reverse rotation ofthe block not only moves the groove side 23 from its blocking position,but also again places the groove side 22 in the path of the strike forengagement thereby when the door is again closed. Thus, when the door isopened, the deadlock is returned to the proper condition for receivingthe strike end when the door is again closed.

It will be recognized from the above that because every time the door isclosed, the relatively massive locking block is brought into the properposition for locking the door, the deadlock of the invention readilylends itself to a simple manipulation to cause the desired locking. Tothis end, a simple releasable locking means is provided for selectivelypreventing rotation of the block in the reverse direction once it is inthe position shown in FIG. 3, thereby preventing the strike from beingremoved from within the groove and, hence, the door from being opened.Such means includes a pin 36 which extends radially outward from thelocking block and through a transversely extending slot 37 in thehousing. The pin 36 rides within such slot 37 upon rotation of thelocking block. In this connection, as shown in FIGS. 3 and 4, the endsof the slot are so positioned that they cooperate with the pin toconstrain the locking block rotation to between positions of the groovecorresponding to when the door is closed and opened.

Pin 36 is rotatably secured within the locking block 18. That is, as isapparent from FIGS. 6 and 7, the pin 36 extends through a bore in thelocking block and terminates in a snubbing end 38 which extends into arecess 39 projecting into the locking block from the side thereofopposite the pin. A locking grip washer 40 is positioned within therecess 39 and receives the snubbing end 38 of the pin 36 to hold the pinwithin the block while allowing it to be rotated with respect to suchblock.

The portion of the pin 36 which rides within the slot 37 does not have acircular transverse cross-section, but rather is provided with adimension in one direction which is less than in another directionorthogonal thereto. It is this dimension relationship and the manner inwhich it coacts with the dimensions of the slot 37 which enable mererotation of the pin to actuate the deadlock to its locked position. Moreparticularly, the pin 36 is provided with shoulders 41 and 42 projectingfrom opposite sides of its side periphery at the location at which suchpin passes through slot 37. As can be seen by comparing FIGS. 8 and 9,the width of the pin when the shoulders 41 and 42 are aligned with thelength of the slot, i.e., when the lesser dimension of the pin extendsin the direction of the slot width, is such that the pin can move alongthe full length of the slot. Thus, the pin will not obstruct rotation ofthe block or movement of the strike end 16 from the groove and, hence,opening of the door. However, when the pin is rotated by ninety degrees,the shoulders on the pin prevent the same from traveling along the slotas shown in FIG. 8. The location of the slot at which it is enlarged topermit rotation of the pin to place such shoulders in the position shownin FIG. 8 is at that end of the slot at which the pin is located whenthe door is closed, i.e., when the groove in the locking block ispositioned to block the return path of the strike.

It will thus be seen that merely by rotating the pin 36, 90, thedeadlock of the invention provides locking of the door in its closedposition. An enlarged head 43 is provided on the free end of the pin tofacilitate such rotation. Moreover, coacting structure is provided onthe pin and the housing to prevent it being rotated any more than theninety degrees necessary to move it between its unlocked and lockedpositions. That is, as can be seen from FIG. 10, an arcuate shoulder 44projects upwardly from the recess 45 with the locking block within whichthe pin shoulders 41 and 42 ride. Such shoulder 44 extends generallysemi-circularly around the pin 36 along that path the shoulder 41 of thepin travels when the pin is rotated between the locked and unlockedpositions shown in FIGS. 8 and 9. As best seen from FIG. 7, the shoulder42 extends further into the recess 45 than does the shoulder 41. Theresult is that the arcuate shoulder 44 in the recess acts as a stopwhich is engaged by the pin shoulder 42 to limit the rotation of suchpin between the locked and unlocked positions.

It will be recognized that when the strike end 16 is received throughthe housing slot and is engaged within the groove 19, such protrudingstrike end is positioned between the upper and lower ends 29 of thehousing. The length dimension ofthe strike end is chosen so that when itis so positioned, any appreciable movement of such strike verticallywithin the slot is prevented. The transversely extending ends 29 of thehousing thus act, in effect, as stops which are spaced axially of thelocking block to constrain vertical movement of the strike relative tothe main structure of the lock. Such vertical movement is thus alsorestrained between the door and the frame and, hence, lifting of thedoor from the frame is prevented.

In order to facilitate its installation on differing door and framedesigns, the preferred embodiment of the invention includes severalfeatures which permit adjustment to assure proper fitting. For one, ascan be seen from FIGS. 3 through 5, the strike 16 is in the form of anangle iron section having one leg, leg 46, longer than its other leg,leg 47. Also, each of the legs is provided with apertures 48 throughwhich fasteners, such as screws 49, can extend to secure the strike to adoor frame so that the other one of the legs is the one which protrudesfrom the frame for receipt within the groove 19 of the cylindricalblock. Moreover, the free ends of both of the legs have a configurationwhich is amenable with such intersection and rotation of the cylindricalblock as described. Thus, either of the legs can be se lected duringinstallation to be the protruding strike leg, merely by turning thestrike over. Because of the different lengths of such legs, differingdistances between the location at which a strike can be secured to aframe and the location at which a main locking structure can be securedto a door can therefore be accommodated.

As another adjustment feature, a shim plate 51 is also included as partof the main structure of the lock. Such shim plate is positionable, ifdesired, between the housing and the door to which such housing is to bemounted, to thereby space the housing from the door. To this end, theshim plate includes a base 52 having a peripheral flange 53 extendingfrom it to define a cavity within which the housing is fittable. As isbest illustrated in FIGS. 3 and 4, a flange 53 extends orthogonally fromthe base on both sides of the latter to thereby define such a cavity oneach side of the base. Moreover, the distance the flange extends beyondthe base on each side thereof is different than the distance it extendstherefrom on the other. It will therefore be recognized that by choosingwhich shim cavity receives the housing when it is mounted on a door, aselected one of the flanges 53 will be made to abut against the door forspacing the shim base and, hence, the housing from such door. Thedifferent dimensions of such flanges thereby permit the shim to be usedto obtain two different spacings of the main structure of the lock fromthe door.

The shim plate 51 is adapted to be independently secured to the door, aswell as secured to such door along with the remainder of the mainstructure of the dealock. More particularly, the base of such shim isprovided with a central aperture 56 which is adapted to receive afastening screw 57. The closure plate 31 for the housing is providedwith a registering aperture 58 to accommodate the head of such screw.The remainder of the main structure of the deadlock is rigidly mountableto the door via screws 59 which extend through apertures 61 adjacent theupper and lower ends of the main member 24 of the housing structure. Asillustrated, such screws also extend through registering apertures 62 inthe shim plate 51. The screws 59 will thus provide a rigid mounting ofthe full main structure of the lock to the door. Furthermore, becausethe structure securing the lock to the door, i.e., the screws 59 and thescrew 49 for the strikeplate, are only accessible from the inside of thedoor, tampering with the same from the exterior is inhibited.

While the inventionhas been described in connection with a preferredembodiment thereof, it will be appreciated by those skilled in the artthat various changes and modifications can be made without departingfrom its scope. For example, the positioning of the. main structure ofthe lock and strike is interchangeable. That is, the protruding strikecan be provided on the door and the main structure on the door frame.Moreover, although the lock is especially designed for usewith slidingglass doors and the like, it will be recognized that it is equally asuseful for locking other closures within their frames. It is thereforeintended that thecoverage afforded applicants be limited only by thelanguage of the claims and its equivalent.

We claim: 7 LA deadlock for securing an opening closure in its closedposition within a frame defining the opening to be closed comprising: anelongated locking block cylinder having a circular cylindrical outerperiphery with an axially extending groove projecting inwardly thereof,which locking block is rotatable on its cylindrical axis for travel ofinwardly and longitudinally extending opposed sides of said groove on acircular cylindrical path; a housing having a cavity therein defined byan interior circular cylindrical section surface which coacts and mateswith said cylindrical outer periphery of said'locking block to definesaid cylindrical path, said housing having a slot extending into saidcavity for passage of a protruding strike endinto said cavity forintersection thereby of said cylindrical path and being rigidlymountable adjacent an edge of one of said opening closure and said frameforsupporting said block at a location at which when said closure is inits closed position, said cylindrical path of said groove sides of saidblock is intersected by said strike end protruding from the other end ofsaid closure and said frame whenever said opening closure is moved toits closed position; said opposed sides of said groove being positionedin said block for engagement of a first one thereof by said strike endupon movement of said closure toward its closed position to rotate saidblock in a first direction and position the second one of said opposedgroove sides blocking the return path said strike end follows when saidclosure is moved toward its open position, and for engagement of saidsecond groove side by said strike end upon movement of said closuretoward its open position to rotate said block in a reverse direction andmove said second groove side from said blocking location and againpositionsaid first groove side in the path of said strike end forengagement thereby when said closure is again moved toward its closedposition; and releasable locking means for selectively preventingrotation of said block in said reverse direction moving said secondgroove side from blocking said return path whereby said closure ismaintained by said deadlock in its closed position, said releasablelocking means including a pin extending generally radially outward fromsaid locking block through a transverse slot in said housing to theexterior thereof for manipulation and movement along said slot upon saidrotation of said locking block, and means on said pin and housingadjacent the periphery of said locking block for preventing movement ofsaid pin from its location in said slot selectively when said secondgroove side of said locking block is positioned blocking the return pathof said strike, whereby said pin and housing are selectively cooperableto prevent rotation of said block in said reverse direction and therebyto lock said closure in its closed position.

2. The deadlock of claim 1 further including transversely extendingstops spaced axially of said locking block and between which saidprotruding strike is positioned when said strike end intersects saidcircular cylindrical path, whereby movement of said strikelongitudinally within said groove is constrained.

3. The deadlock of claim 1 wherein said pin has in transversecross-section a dimension in one direction which is less than in anotherdirection orthogonal thereto, and said slot has a width along its lengthaccommodating movement of said pin therealong when said lesser dimensionof said pin extends in the direction of said width but preventingmovement of said .pin from its location at which said second groove sideof said locking block is positioned blocking the return path of saidstrike when the greater dimension of said pin extends in the directionof said width, whereby rotation of said pin by exterior manipulation toplace said longer dimension in the direction of the width of said slotresults in said pin and housing cooperating to prevent said rotation ofsaid block in said reverse direc-- tion.

4. The deadlock of claim 2 wherein said housing is provided by a mainmember having a generally semicylindrical reentrant portion definingsaid cavity circular cylindrical section surface, axially opposed endsof said'reentrant portion providing said stops for constraininglongitudinal movement of said strike end when positioned within saidcavity; said cylindrical locking block extending for the full length ofsaid reentrant portion cavity and having end projections on thecylindrical axis thereof engageable with said reentrant portion opposedends to define bearings for said rotation'of said locking block.

5. The deadlock of claim 3v further including cooperable means on saidpin and said housing preventing rotation of said pin other than betweensaid positions placing said lesser and said greater dimensions thereofin the direction of the width of said slot.

1. A deadlock for securing an opening closure in its closed positionwithin a frame defining the opening to be closed comprising: anelongated locking block cylinder having a circular cylindrical outerperiphery with an axially extending groove projecting inwardly thereof,which locking block is rotatable on its cylindrical axis for travel ofinwardly and longitudinally extending opposed sides of said groove on acircular cylindrical path; a housing having a cavity therein defined byan interior circulAr cylindrical section surface which coacts and mateswith said cylindrical outer periphery of said locking block to definesaid cylindrical path, said housing having a slot extending into saidcavity for passage of a protruding strike end into said cavity forintersection thereby of said cylindrical path and being rigidlymountable adjacent an edge of one of said opening closure and said framefor supporting said block at a location at which when said closure is inits closed position, said cylindrical path of said groove sides of saidblock is intersected by said strike end protruding from the other end ofsaid closure and said frame whenever said opening closure is moved toits closed position; said opposed sides of said groove being positionedin said block for engagement of a first one thereof by said strike endupon movement of said closure toward its closed position to rotate saidblock in a first direction and position the second one of said opposedgroove sides blocking the return path said strike end follows when saidclosure is moved toward its open position, and for engagement of saidsecond groove side by said strike end upon movement of said closuretoward its open position to rotate said block in a reverse direction andmove said second groove side from said blocking location and againposition said first groove side in the path of said strike end forengagement thereby when said closure is again moved toward its closedposition; and releasable locking means for selectively preventingrotation of said block in said reverse direction moving said secondgroove side from blocking said return path whereby said closure ismaintained by said deadlock in its closed position, said releasablelocking means including a pin extending generally radially outward fromsaid locking block through a transverse slot in said housing to theexterior thereof for manipulation and movement along said slot upon saidrotation of said locking block, and means on said pin and housingadjacent the periphery of said locking block for preventing movement ofsaid pin from its location in said slot selectively when said secondgroove side of said locking block is positioned blocking the return pathof said strike, whereby said pin and housing are selectively cooperableto prevent rotation of said block in said reverse direction and therebyto lock said closure in its closed position.
 2. The deadlock of claim 1further including transversely extending stops spaced axially of saidlocking block and between which said protruding strike is positionedwhen said strike end intersects said circular cylindrical path, wherebymovement of said strike longitudinally within said groove isconstrained.
 3. The deadlock of claim 1 wherein said pin has intransverse cross-section a dimension in one direction which is less thanin another direction orthogonal thereto, and said slot has a width alongits length accommodating movement of said pin therealong when saidlesser dimension of said pin extends in the direction of said width butpreventing movement of said pin from its location at which said secondgroove side of said locking block is positioned blocking the return pathof said strike when the greater dimension of said pin extends in thedirection of said width, whereby rotation of said pin by exteriormanipulation to place said longer dimension in the direction of thewidth of said slot results in said pin and housing cooperating toprevent said rotation of said block in said reverse direction.
 4. Thedeadlock of claim 2 wherein said housing is provided by a main memberhaving a generally semi-cylindrical reentrant portion defining saidcavity circular cylindrical section surface, axially opposed ends ofsaid reentrant portion providing said stops for constraininglongitudinal movement of said strike end when positioned within saidcavity; said cylindrical locking block extending for the full length ofsaid reentrant portion cavity and having end projections on thecylindrical Axis thereof engageable with said reentrant portion opposedends to define bearings for said rotation of said locking block.
 5. Thedeadlock of claim 3 further including cooperable means on said pin andsaid housing preventing rotation of said pin other than between saidpositions placing said lesser and said greater dimensions thereof in thedirection of the width of said slot.